So far, I thought CoffeeScript as something neat to use. After going through the slides, I now think it is not worth it for a mildly seasoned javascript programmer. I can see how it could help a newcomer to avoid javascript pitfalls, but those pitfalls could also be covered with a few commandments to follow.
I'm what I would consider a "well-seasoned" JavaScript developer and disagree. I think CoffeeScript is better for people who already know JavaScript decently well than newbies. CoffeeScript doesn't help you avoid learning JavaScript, it just makes it more pleasant.